JRE 8 rt.jar is the JAR file for JRE 8 RT (Runtime) libraries. JRE (Java Runtime) 8 is the runtime environment included in JDK 8. JRE 8 rt.jar libraries are divided into 6 packages:

com.* - Internal Oracle and Sun Microsystems libraries
java.* - Standard Java API libraries.
javax.* - Extended Java API libraries.
jdk.* -  JDK supporting libraries.
org.* - Third party libraries.
sun.* - Old libraries developed by Sun Microsystems.

JAR File Information:

Directory of C:\fyicenter\jdk-1.8.0_191\jre\lib
      63,596,151 rt.jar

Here is the list of Java classes of the javax.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ javax/management/DefaultLoaderRepository.java

/*
 * Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package javax.management;

import javax.management.loading.ClassLoaderRepository;

/**
 * <p>Keeps the list of Class Loaders registered in the MBean Server.
 * It provides the necessary methods to load classes using the registered
 * Class Loaders.</p>
 *
 * <p>This deprecated class is maintained for compatibility.  In
 * previous versions of the JMX API, there was one
 * <code>DefaultLoaderRepository</code> shared by all MBean servers.
 * As of version 1.2 of the JMX API, that functionality is
 * approximated by using {@link MBeanServerFactory#findMBeanServer} to
 * find all known MBean servers, and consulting the {@link
 * ClassLoaderRepository} of each one.  It is strongly recommended
 * that code referencing <code>DefaultLoaderRepository</code> be
 * rewritten.</p>
 *
 * @deprecated Use
 * {@link javax.management.MBeanServer#getClassLoaderRepository()}
 * instead.
 *
 * @since 1.5
 */
@Deprecated
public class DefaultLoaderRepository {
    /**
     * Go through the list of class loaders and try to load the requested class.
     * The method will stop as soon as the class is found. If the class
     * is not found the method will throw a <CODE>ClassNotFoundException</CODE>
     * exception.
     *
     * @param className The name of the class to be loaded.
     *
     * @return the loaded class.
     *
     * @exception ClassNotFoundException The specified class could not be found.
     */
    public static Class<?> loadClass(String className)
        throws ClassNotFoundException {
        return javax.management.loading.DefaultLoaderRepository.loadClass(className);
    }


    /**
     * Go through the list of class loaders but exclude the given class loader, then try to load
     * the requested class.
     * The method will stop as soon as the class is found. If the class
     * is not found the method will throw a <CODE>ClassNotFoundException</CODE>
     * exception.
     *
     * @param className The name of the class to be loaded.
     * @param loader The class loader to be excluded.
     *
     * @return the loaded class.
     *
     * @exception ClassNotFoundException The specified class could not be found.
     */
    public static Class<?> loadClassWithout(ClassLoader loader,String className)
        throws ClassNotFoundException {
        return javax.management.loading.DefaultLoaderRepository.loadClassWithout(loader, className);
    }

 }

⏎ javax/management/DefaultLoaderRepository.java

Or download all of them as a single archive file:

File name: jre-rt-javax-1.8.0_191-src.zip
File size: 5381005 bytes
Release date: 2018-10-28
Download 

⇒ JRE 8 rt.jar - org.* Package Source Code

⇐ JRE 8 rt.jar - java.* Package Source Code

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